title: Miocene-Pliocene speciation, introgression, and migration of Patis and Ptilagrostis (Poaceae: Stipeae).
abstract: Genetic interchange between American and Eurasian species is fundamental to our understanding of the biogeographical patterns, and we make a first attempt to reconstruct the evolutionary events in East Asia that lead to the origin and dispersal of two genera, Patis and Ptilagrostis. We conducted a molecular phylogenetic study of 78 species in the tribe Stipeae using four plastid DNA sequences (ndhF, rpl32-trnL, rps16-trnK, and rps16 intron) and two nuclear DNA sequences (ITS and At103). We use single copy nDNA gene At103 for the first time in the grasses to elucidate the evolutionary history among members of the Stipeae. Ampelodesmos, Hesperostipa, Oryzopsis, Pappostipa, Patis, and Stipa are found to be of multiple origins. Our phylograms reveal conflicting positions for Ptilagrostis alpina and Pt. porteri that form a clade with Patis coreana, P. obtusa, and P. racemosa in the combined plastid tree but are aligned with other members of Ptilagrostis in the ITS tree. We hypothesize that Ptilagrostis still retains the nucleotype of an extinct genus which transited the Bering land bridge from American origins in the late Miocene (minimum 7.35-6.37 mya) followed by hybridization and two plastid capture events with a Trikeraia-like taxon (7.96 mya) and para-Patis (between 5.32 and 3.76 mya). Ptilagrostis porteri and Patis racemosa then migrated to continental North America 1.7-2.9 mya and 4.3-5.3 mya, respectively.
authors.affiliation: Smithsonian Institution, Department of Botany, MRC-166, National Museum of Natural History, Washington, DC 20013-7012, USA; M.G. Kholodny Institute of Botany, National Academy of Sciences of Ukraine, 01601 Kiev, Ukraine; Laboratory of Molecular Systematics, Botanic Institute of Barcelona, (IBB-CSIC-ICUB), Passeig del Migdia s.n., 08038 Barcelona, Spain.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Romaschenko
authors.forename: Nuria
authors.initials: N
authors.lastname: Garcia-Jacas
authors.forename: Paul M
authors.initials: PM
authors.lastname: Peterson
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Soreng
authors.forename: Roser
authors.initials: R
authors.lastname: Vilatersana
authors.forename: Alfonso
authors.initials: A
authors.lastname: Susanna
mesh_terms: D001499:Bayes Theorem; D018744:DNA, Plant / Q000235:genetics; D019143:Evolution, Molecular; D010802:Phylogeny; D018087:Plastids / Q000235:genetics; D006109:Poaceae / Q000033:anatomy & histology / Q000145:classification / Q000235:genetics*; D017422:Sequence Analysis, DNA
chemical_list: D018744:DNA, Plant
keywords: At103; Biogeography; Classification; Low copy nuclear DNA sequences; Patis; Phylogeny